Hello,         I keep reading about how dynamic redefinition of functions (which I understand is often mischaracterized as "incremental compilation") is a big benefit of lisp and scheme, increases productivity,etc, but I cannot find any examples or how-to documents anywhere. I am trying to find out how to do this in PLT. I need to interact via keyboard/mouse with my running program in a window and still be able to redefine a function and have it take effect as soon as I hit "enter" in DrScheme. Can this be done (easily)? Do I have to have a thread for my "main" program and another for a REPL?